If left undetected and untreated, reduced vision in one eye can lead to monocular blindness in an amblyopic eye. Most vision screening is conducted on children once they have started kindergarten;this is after the critical detection period for the treatment of amblyopia. Early detection is essential for favorable prognosis. Unfortunately less than 21% of pre-kindergarten children receive any sort of vision screening. National Genecular Institute Holdings, Inc. (NGIh) has built and begun testing and optimization of a digital photorefractor that can be used to screen preverbal and preliterate children for amblyogenic risk factors. NGIh's technology will streamline the screening process and reduce the overall time and cost of vision screening. The NGIh Digital Photorefractor (DPR) will offer all screening programs a device with a high specificity and sensitivity. Specifically this Phase I study aims to: 1) Optimize the parameter of flash width, 2) Optimize the parameter of exposure time and image interval, and 3) Optimize DPR performance by testing additional flash eccentricities. Results from this study will provide the necessary data for the design of the optimized DPR test product for clinical evaluation in Phase II. PUBLIC HEALTH RELEVANCE: National Genecular Institute Holdings, Inc. (NGIh) is developing a digital photorefractor (DPR) to assist in the screening of preliterate and preverbal children for amblyopia (lazy eye). This system images the corneal light reflex, bright crescents, and the Bruckner reflex to screen children for amblyogenic risk factors. It represents a faster, non-invasive, non-contact tool to detect significant causes of monocular blindness. This Phase I study will provide testing for performance optimization using in-vitro methods. The optimized DPR technology will then be ready for future Phase II clinical studies.